<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>scan</title>
    <script src="https://unpkg.com/html5-qrcode"></script>
    <style>
        button {
            display: block;
            width: 100%;
            margin: 6px;
            outline: none;
            height: 40px;
            line-height: 40px;
            color: #fff;
            background-color: #26a2ff;
            text-align: center;
            border-radius: 4px;
            border: none;
            cursor: pointer;
        }

        #upload-input {
            opacity: 0;
            filter: alpha(opacity=0);
            display: inline-block;
            width: 100%;
            height: 100%;
        }

        #upload-text {
            position: relative;
            bottom: 40px;
            user-select: none;
        }
    </style>
</head>

<body>
    <!-- 相机、文件方式同时只能使用一个,可根据自己需求修改,如:1.改成下拉框;2.改成tab;3.改成radio等等控制显示隐藏和相应逻辑 -->
    <button onclick="useCamera()">使用相机扫一扫方式</button>
    <button onclick="useLocal()">
        <input type="file" id="upload-input" accept="image/*" value="使用文件方式">
        <span id="upload-text">使用文件方式</span>
    </button>
    <div id="reader"></div>
    <h3 id="qr-reader-results"></h3>
    <script>
        //方式一使用库的ui
        // var resultContainer = document.getElementById('qr-reader-results');
        // var lastResult, countResults = 0;



        // var html5QrcodeScanner = new Html5QrcodeScanner("reader", { fps: 10, qrbox: 300 });
        // html5QrcodeScanner.render(onScanSuccess);
        // var resultContainer = document.getElementById('qr-reader-results');
        // var lastResult, countResults = 0;


        //1.Html5QrcodeScanner是js提供的ui; 2.Html5Qrcode是自定义面板
        let html5QrCode = new Html5Qrcode("reader");
        let reader = document.getElementById("reader");
        let res = document.getElementById('qr-reader-results');
        let uploadInput = document.getElementById('upload-input');
        let config = { fps: 10, qrbox: { width: 300, height: 280 } }; //扫一扫相关设置

        //使用本地文件
        function useLocal() {

            reader.style.display = "none";
            res.innerText = "";
            uploadInput.addEventListener("change", (e) => {
                if (e.target.files.length == 0) {
                    return;
                }
                const imageFile = e.target.files[0];
                html5QrCode
                    .scanFile(imageFile, true)
                    .then((res) => {
                      console.log("res",res)
                        res.innerText = "扫码成功结果:\n" + res;
                    })
                    .catch((err) => {
                      console.error("err",err)
                        res.innerText = "扫码失败:\n" + err;
                    });
            });
        }

       //相机授权
        function useCamera() {
            alert("aa")
          console.log("navigator.mediaDevices",navigator.mediaDevices)
          if (navigator.mediaDevices === undefined) {
            navigator.mediaDevices = {};
          }
          if (navigator.mediaDevices.getUserMedia === undefined) {
            navigator.mediaDevices.getUserMedia = function (constraints) {
              var getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia || navigator.oGetUserMedia;
              if (!getUserMedia) {
                return Promise.reject(new Error('getUserMedia is not implemented in this browser'));
              }
              return new Promise(function (resolve, reject) {
                getUserMedia.call(navigator, constraints, resolve, reject);
              });
            }
          }
          alert("bbb")
            reader.style.display = "block";
            res.innerText = "";
            Html5Qrcode.getCameras()
                .then((devices) => {
                  console.log("devices=========",devices)
                    if (devices && devices.length) {
                        let cameraId = "";
                        if (devices.length == 1) {
                            cameraId = devices[0].id; //前置摄像头
                        } else {
                            cameraId = devices[1].id;  //后置摄像头
                        }
                        if (cameraId) {
                            startWithCameraId(cameraId);
                        }
                    } else {
                        startWithoutCameraId();
                    }
                })
                .catch((err) => {
                    console.error("没有获取摄像头设备...===============",err);
                });
        }

        //带相机ID扫描
        function startWithCameraId(cameraId) {
            html5QrCode
                .start(
                    { deviceId: { exact: cameraId } },
                    config,
                    onScanSuccess,
                    onScanFailure
                )
                .catch((err) => {
                    console.log("通过摄像头扫码异常....", err);
                });
        }

        //不带相机ID扫描,允许传递约束来代替相机设备 ID
        function startWithoutCameraId() {
            //environment 表示后置摄像头  换成user则表示前置摄像头
            html5QrCode.start(
                { facingMode: "environment" } || {
                    facingMode: { exact: "environment" },
	   qrbox: { width: 250, height: 250 }
                },
                config,
                onScanSuccess,
                onScanFailure
            );
        }

        //扫码解析成功后按照自己的需求做后续的操作
        function onScanSuccess(a, decodedResult) {
            res.innerText = "扫码成功结果:\n" + a;
        }

        //扫码解析失败后按照自己的需求做后续的操作
        function onScanFailure(error) {
            res.innerText = "扫码失败:\n" + error;
        }
    </script>

</body>

</html>
